The present invention relates to an articulated ladder assembly and more particularly to an adjustable position ladder assembly which includes a novel hinge and lock joint assembly for connecting pairs of adjacent ladder rails, a novel reinforced structure for assembling pairs of ladder rails with the hinge assembly and a novel stabilizer bar readily adaptable to various angular positions of the ladder assembly.
Articulated ladder assemblies are generally well known in the art including those having adjustable coupling hinges on pairs of adjacent rails which include rotatable facing disks which can be held in locked relation of more than one preselected angular position. In this regard, attention is directed to U.S. Pat. No. 4,474,264, issued to G. Krause on Oct. 2, 1984, to No. 4,543,006, issued to Chien-Yuan Wang on Sep. 24, 1985, and to No. 4,648,481, issued to Dickey Lee on Mar. 10, 1987, each of which patents teaches such a facing relatively rotatable disk assembly, each assembly having spaced peripheral disk notches engageable by a spring loaded releasable pawl. Attention further is directed to U.S. Pat. No. 4,666,327, issued to George Su on May 19, 1987, which teaches a spaced, bifurcated disk member, relatively moveable to a sandwiched disk inserted therebetween, the disks having alignable apertures adapted to receive a depending pin to lock the disks at various preselected annular positions. Attention also is directed to the Multi-Master and MultiMatic bulletins of R. D. Werner Co., Inc. and Krause Company, respectively, which teach adjustable position peripheral lock hinges and cured surface stabilizing bars for end ladder rail sections. Finally, attention is directed to the Jaws Ladder Mfg., Inc. of Weston, Ontario, Canada bulletin, which teaches an intermeshing teeth, hingelock system with the intermeshed teeth being locked into position through a centrally disposed hinge screw-lock handle.
In accordance with the present invention, an improved ladder assembly is provided which is straightforward, efficient and economical in manufacture, assembly and operation, requiring a minimum of parts and providing a stable support in positively locked alternative ladder positions. Further, the present invention provides a unique multi-teeth intermeshing arrangement which optimizes shear strength and which allows for ready adjustment to preselected angular positions, to be releasably held in such preselected positions by a comparatively straightforward and easy to operate snap-lock arrangement. In addition, the present invention provides a unique readily assembled, strength reinforced hinge and rail structure and a unique stabilizing structure for a ladder which provides maximum ground contact and ladder stability at more than one preselected angular position of the ladder.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein. In this regard, it is to be understood that several of the disclosed features of the present invention are not to be considered as limited to the particular articulated ladder assembly described herein but that such unique features as the intermeshing teeth, hinge locking assembly, the wrap around structural reinforcing arrangement and the multi-faced stabilizing bar can be utilized in other types of ladder assemblies.